The MiniMed 640G comes in two varieties: one with a continuous glucose measurement (CGM) system, and one with a traditional glucose meter. I didn’t want the CGM variant as I’m not too keen on having a secondary injection site for the CGM sensor, and I don’t want to grow over-dependent on another integrated system. My feelings about that last point is mostly influenced by the 2014 essay Modern Life Without a Pancreas; which I highly recommend reading.

The bundled glucose meter option comes wit the Contour Next Link. It’s essentially the same meter as the Contour Next One except it doesn’t have the same sleek black design, charges over USB, has an actual color display, and it has an extra Off/Menu button.

Testing takes the same amount of time as on the Contour Next One. The Next Link has a logbook system where you can flag your measurements to remind yourself about physical activity, mealtimes, and other factors that affect your glucose levels. The biggest difference between the two meters becomes evident when testing is complete.

You can turn off the Next One meter by removing the test strip or holding the primary button. You must leave the meter turned on for several seconds with the Contour Diabetes app open at the same time to synchronize the two. The Next Link isn’t compatible with the Contour Diabetes app but rather transmits the result to the test to the insulin pump. You can review past test results on the pump and see them in a log book together with a log of insulin injections.

The Next One uses Bluetooth while the Next Link communicates with the pump over the Zigbee protocol (both protocols in addition to WiFi are variants of the IEEE 802 standard.) Zigbee is used for internet-of-things (IoT) devices like store price tags and light bulbs whereas Bluetooth is a more common choice for computer and phone accessories.

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I’ve all but given up on turning off the Next Link after use, however. Unlike the Next One, removing the test strip doesn’t turn the device off. Holding the Off button pressed only works intermittently. I’ve learned to just leave it turned on until it eventually times out and turns itself off. I’ve only had the meter for about a month, and I’ve already had to charge it three times.

The Next Link can send insulin injection commands to the MiniMed 640G directly. This can be very useful for people with physical disabilities or guardians wanting to remotely administrating their kid’s treatment. I’ve found the remote injection system to be frustratingly slow to use. The meter has to reconnect to the pump (technically, it’s switching connection mode) which takes time, and you’re given fewer delivery options than when you’re just using the pump manually. You can only set an immediate injection and not use some of the pumps more granular delivery options like square delivery or time delayed injections.

Using the connected glucose meter with the pump also slows down interactions directly with the pump. After you’ve performed a test and seen the result on the Next Link, you also get to see the same result again on the pump on a separate screen that you have to dismiss. It sometimes takes a bit of time before this screen appears on the pump, so you could be interrupted by this screen half-way through the manual injection process.

It takes me more time to do a glucose test and set an insulin injection with the Next Link than the Next One. The meter is slower and its connectivity with the pump ends up adding more delays than it adds convenience.

I really prefer using the pump and meter separate from each other as their interaction doesn’t really give me any added convenience or benefits. I’ve disabled the remote injection feature on the pump and disconnected the meter syncing entirely. I’m now using the Contour Next One again, which despite its flaws and buggy companion app experience is better for every day use than the Next Link.